Fundus photography device

ABSTRACT

A fundus photography device includes: an OCT optical system configured to detect interference between a measurement light from a fundus of a subject&#39;s eye and a reference light from a reference optical path; a fundus photography optical system configured to detect a reflected light from the fundus; a controller configured to generate a tomographic image of the fundus and a first front image of the fundus based on an output signal from the OCT optical system, and generate a second front image of the fundus based on an output signal from the fundus photography optical system. The controller is configured to cause simultaneous display of the first front image and the second front image in different display regions on a monitor.

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority ofJapanese Patent Application No. 2014-074597 filed on Mar. 31, 2014, thecontents of which are incorporated herein by reference in its entirety.

BACKGROUND

The present invention relates to a fundus photography device thatphotographs the fundus of a subject's eye.

In the related art, there is known an optical coherence tomography (OCT)using low-coherent light as an ophthalmic device that can non-invasivelyphotograph a tomographic image of a subject's eye. A compound device ofthe OCT and a fundus camera is proposed (refer to JP-A-2013-056274).

In the related art, for example, a scanning position is set using aninfrared fundus image photographed by an infrared camera provided in thefundus camera. However, the infrared fundus image does not necessarilyhave good resolution, and is not suitable for OCT photography.

A technique of generating a front image from a signal obtained using OCTis known, but is not suitable for photography performed by the funduscamera. For example, an inspector cannot observe a flare, and cannotconfirm a focus index and an alignment index.

SUMMARY

The present invention is made in light of this problem, and an object ofthe present invention is to provide a fundus photography device that canproperly perform each adjustment.

The present invention has the following configuration so as to achievethe object.

According to an aspect of the present invention, the followingarrangements are provided:

A fundus photography device comprising:

-   -   an OCT optical system configured to detect interference between        a measurement light from a fundus of a subject's eye and a        reference light from a reference optical path;    -   a fundus photography optical system configured to detect a        reflected light from the fundus; and    -   a controller configured to generate a tomographic image of the        fundus and a first front image of the fundus based on an output        signal from the OCT optical system, and generate a second front        image of the fundus based on an output signal from the fundus        photography optical system,    -   wherein the controller is configured to cause simultaneous        display of the first front image and the second front image in        different display regions on a monitor.

A fundus photography device comprising:

-   -   an OCT optical system configured to detect interference between        a measurement light from a fundus of a subject's eye and a        reference light from a reference optical path;    -   a fundus photography optical system configured to detect        reflected light from the fundus;    -   an index projection optical system configured to project light        of an index onto the subject's eye; and    -   a controller configured to cause (1) display of a scanning line        indicating a measurement position of a tomographic image on a        first front image generated based on an output signal from the        OCT optical system or from the fundus photography optical        system, and (2) display of an image of the index on a second        front image generated based on the fundus photography optical        system.

A fundus photography device comprising:

-   -   an interference optical system including:        -   an optical splitter configured to divide built from an OCT            light source into a measurement optical path and a reference            optical path,        -   an optical scanner configured to scan measurement light from            the measurement optical path onto a fundus of a subject's            eye, and        -   a light detector configured to detect combined light            obtained by combining fundus-reflected light produced by the            measurement light reflected by the fundus and reference            light from the reference optical path;    -   an OCT image processor configured to generate a tomographic        image of the fundus based on an output signal from the light        detector, and a first front image that is a front observation        image of the fundus;    -   a fundus illumination optical system configured to        simultaneously illuminate two-dimensional regions on the fundus        of the subject's eye;    -   a fundus photography optical system configured to photograph a        front image of the fundus with a two-dimensional imaging sensor;        and    -   a display controller configured to control a display of a        monitor to simultaneously display the first front image and a        second front image in different-display regions, the second        front image being generated based on the two-dimensional imaging        sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show schematic views illustrating the exterior of afundus photography device according to an embodiment.

FIG. 2 is a view illustrating an optical system and a control system ofthe fundus photography device according to the embodiment.

FIG. 3 is a view illustrating an example of a screen displayed on adisplay unit according to the embodiment.

FIGS. 4A and 4B illustrate an example in which an anterior chamber imagecaptured by an imaging element is displayed on the display unit.

FIG. 5 is a block diagram illustrating the control system according tothe embodiment.

FIGS. 6A and 6B show graphs illustrating the detection of alignment withrespect to a subject's eye.

FIG. 7 is a flowchart illustrating an example of a photographicoperation according to the embodiment.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

A typical embodiment of the present invention will be described withreference to the accompanying drawings. In the following description ofthe embodiment, a Z direction (a direction of an optical axis L1) refersto a direction of the depth of a subject's eye, an X direction refers toa horizontal component on a plane (a plane being flush with a subject'sface) perpendicular to the direction of the depth, and a Y directionrefers to a vertical component on the plane.

<First Outline>

A device 1 mainly includes a coherence optical system (an OCT opticalsystem) 200; a fundus illumination optical system (hereinafter, may bereferred to as an illumination optical system) 10; a fundus photographyoptical system (hereinafter, may be referred to as a photography opticalsystem) 30; and a controller (for example, a PC 90 and a controller 70)(refer to FIG. 2). An optical axis L2 of the coherence optical system200 is disposed coaxially with an optical axis L1 of the fundusillumination optical system 10 and the fundus photography optical system30 by using an optical path division member. Naturally, the optical axisL1 may not coaxial with the optical axis L2.

<OCT>

The coherence optical system 200 may be provided so as to obtain atomographic image of a fundus Ef of a subject's eye using opticalcoherence tomography. The coherence optical system 200 includes asplitter (a light divider); light scanning unit; and light detector (aphotodetector).

The splitter (for example, a coupler 104) may be provided so as todivide light from an OCT light source (for example, a measurement lightsource 102) into light via a measurement optical path and light via areference optical path. The measurement light path (for example, a fibersystem or a lens system) may be configured to guide measurement light tothe fundus Ef. The reference optical path may be configured to advancereference light in the device and to induce coherence between thereference light and the measurement light.

The light scanning unit (for example, the scanning unit 108) may beprovided so as to scan the measurement light on the fundus Ef. Forexample, the fight scanning unit may be disposed on the measurementlight path, and scan the measurement fight to be illuminated on thefundus of the subject's eye via the measurement light path.

The light detector (for example, a detector 120) may be provided so asto detect light that is obtained by combining fundus-reflected lightproduced by the measurement light from the measurement light path andthe light from the reference optical path. A combiner may combine themeasurement light from the measurement optical path reflected by thefundus Ef and the reference light from the reference optical path. Abeam splitter, a half mirror, a fiber coupler, a circulator, or the likeis used as the splitter and the combiner.

The controller (for example, the PC 90 and the controller 70) as an OCTimage acquisition unit may control the light scanning unit to scan themeasurement light, and acquire at least a tomographic image of thefundus Ef based on an output signal from the light detector. Inaddition, the controller may control the light scanning unit to scan themeasurement light, and acquire a tomographic image of the fundus Efbased on an output signal from the light detector, and a first frontimage (for example, an OCT front image 84) (a front observation image)based on an output signal from the light detector.

In regard to the acquisition of a tomographic image, for example, thecontroller may control the light scanning unit to scan the measurementin a vertical direction, and acquire a tomographic image of the fundusEf based on an output signal from the light detector. The controller maycontrol the light scanning unit and acquire a tomographic imagecorresponding to a scanning position set in response to an operationsignal generated by an inspector, or the controller may control thelight scanning unit and acquire a tomographic image corresponding to ascanning position stored in a storage unit (for example, a memory 72).The scanning position may be changed vertically and laterally withrespect to the fundus Ef, or may be changed in a rotation direction withrespect to the fundus Ef.

In addition, the controller may control the light scanning unit andacquire a tomographic image corresponding to a scanning pattern set inresponse to an operation signal generated by an inspector, or thecontroller may control the light scanning unit and acquire a tomographicimage corresponding to a scanning pattern stared in the storage unit.The scanning pattern may be a line scan or a circle scan. A cross scan,a radial scan, a multiple line scan, a raster scan (a map scan), and thelike are examples of the scanning pattern in which a plurality ofdifferent scanning lines are arrayed.

In regard to the acquisition of the first front image, the controllermay control the light scanning unit to scan the measurement light in twodimensions (for example, raster scan), and acquire the first front image(for example, the OCT front image 84) (front observation image) of thefundus Ef based on an output signal from the light detector.

For example, the controller may acquire the first front image based onthe phase of a spectroscopic signal at each X-Y position. At this time,the controller may generate the first front image based on the number ofzero cross points of a coherence signal (for example, refer toJP-A-2011-215134). The controller 70 may acquire the first front imagebased on the intensity of a spectroscopic signal at each X-Y position.

For example, after the controller generates three-dimensional OCT databased on a spectroscopic signal at each position, the controller maygenerate the first front image based on the three-dimensional OCT data.At this time, the controller may acquire the first front image byintegrating signal intensity distributions (distributions in a directionof the depth of the subject's eye) of the three-dimensional OCT data atthe X-Y positions. The first front image may be a retina outer layer OCTimage, or may be a C scan image indicative of a signal intensitydistribution at a constant depth position. The first front image is notlimited to the above-mentioned images, and may be a fundus observationimage obtained by performing a specific analysis process of a detectionsignal from the light detector.

The acquired first front image may be displayed in a live mode on thedisplay unit. At this time, the controller may alternately acquire thefirst front image and a first tomography image corresponding to a setscanning pattern by controlling the light scanning unit. At this time,the first front image and the tomographic image may be alternatelyacquired once at a time. Alternatively, the first front images areacquired multiple times, and then the first tomographic image (one firsttomographic image or a plurality of the first tomographic images) may beacquired. At least one first front image may be acquired, and then aplurality of the first tomographic images may be acquired.

It is possible to acquire a high-resolution tomographic image by settinga scanning speed during the acquisition of the tomographic image to behigher than that during the acquisition of the front image. Thetomographic image may be extracted from the three-dimensional OCT dataused as an original data of the first front image, and may be displayed.

The first front image as a live image may be an image (for example, anadded average image) obtained by combining a plurality of the firstfront consecutive images. The controller may perform a scan multipletimes at each position, and acquire the first front image based on aplurality of spectroscopic signals. The tomographic image may also bedisplayed in a live mode on the display unit.

The controller may acquire the first front image by controlling thelight scanning unit, and acquire the tomographic image corresponding tomeasurement positions set on the first front image displayed on thedisplay unit.

<FC>

The fundus illumination optical system 10 may be provided so as tosimultaneously illuminte a two-dimensional region on the fundus Ef byillumination light. At this time, the fundus illumination optical system10 includes a photography light source 14 and an observation lightsource 11, and may simultaneously illuminate the two-dimensional regionon the fundus Ef by illumination light from at least either one of thephotography light source 14 and the observation light source 11. Thephotography light source 14 and the observation light source 11 may beseparate light sources, or may be the same light source.

For example, the illumination optical system 10 may be provided so as toilluminate the fundus Ef by the illumination light via a mirror portion22 b of a hole mirror and an objective lens 25. The illumination lightmay be at least either one of the visible light and the infrared light.The infrared light is preferably used as the illumination light so as toprevent an occurrence of mydriasis, and the illumination optical system10 may include a visible light illumination optical system thatilluminates the fundus Ef by the visible light, and an infrared lightillumination optical system that illuminates the fundus Ef by theinfrared light.

The fundus photography optical system 30 may be provided so as tophotograph a front image of the fundus Ef illuminated by theillumination light using a two-dimensional imaging element. In thiscase, the fundus photography optical system 30 may include a (first)two-dimensional imaging element 35 that photographs the fundus, and a(second) two-dimensional imaging element 38 for observing the fundus,and may photograph a front image of the fundus Ef illuminated by theillumination light. The imaging element for photography and the imagingelement for observation may be respectively formed of different imagingelements, or may be formed of the same imaging element. The imagingelements may be disposed conjugately with the fundus.

The fundus photography optical system 30 may be provided so as tophotograph a front image of the fundus Ef illuminated by theillumination light of the illumination optical system 10 via an opening22 a of a hole mirror 22. The fundus photography optical system 30 mayinclude a focusing lens 32 that can move in an optical axis direction.

The fundus photography optical system 30 may include a (first) imagingelement (for example, the two-dimensional imaging element 35) thatphotographs a still image of the fundus, and a second imaging element(for example, the two-dimensional imaging element 38 (two-dimensionalimaging sensor)) for observing the fundus in a moving picture mode. Theimaging element for photography and the imaging element for observationmay be respectively formed of different imaging elements, or may beformed of the same imaging element. The fundus illumination opticalsystem 10 and the fundus photography optical system 30 may form a funduscamera optical system 100 that photographs the fundus of the subject'seye.

<Display (for example, refer to FIG. 3) of First Front Image (forexample, OCT Front Image 84) and Second Front Image (for example, FCFront Image 82)>

The controller (for example, the PC 90 and the controller 70) may beused as display controller. The display controller controls a display ofthe display unit (for example, a display unit 75 and a display unit 95).At this time, for example, the display controller may simultaneouslydisplay the first front image and a second front image in differentdisplay regions. Here, the first front image is based on the outputsignal from the light detector of the coherence optical system 200, andthe second front image is a front observation image of the fundus Efbased on an imaging signal from the two-dimensional imaging element ofthe fundus photography optical system 30 (refer to FIG. 3).

Accordingly, it is possible to properly adjust the coherence opticalsystem 200 using the first front image and the fundus illuminationoptical system 10 or the fundus photography optical system 30 using thesecond front image. The adjustment of the coherence optical system 200may be the adjustment of a scanning position, the adjustment of theposition of a fixation lamp, the adjustment of a focus, the control of apolarized wave, or the like. The adjustment of the fundus illuminationoptical system 10 or the fundus photography optical system 30 may be theadjustment of alignment or a focus with respect to the subject's eye. Asa result, it is possible to smoothly photograph a good tomographic imageand a good fundus front image (for example, a color fundus image or afluorescent fundus image).

The first front image and the second front image are preferablydisplayed as live images. The inspector can easily understand a state ofthe subject's eye or the device while watching the live images.

The display controller may simultaneously display the first front imageand the second front image in different display regions. Here, the firstfront image is based on the output signal from the light detector of thecoherence optical system 200, and the second front image is a frontobservation image of the fundus Ef based on the imaging signal from the(second) two-dimensional imaging element 38 for observing the fundus.

When the first front image and the second front image are simultaneouslydisplayed in different display regions, the display controller maydisplay the first front image and the second front image in differentregions on a display screen of the same display unit (refer to FIG. 3).At this time, for example, the display controller may display the firstfront image in a first display region on the display unit, and displaythe second front image in a second display region different from thefirst display region. The first front image and the second front imagemay be displayed vertically or laterally side by side. The first frontimage and the second front image may be displayed while being separatedfrom each other. The first front image and the second front image may bedisplayed in different sizes, or may be displayed in the same size. Inthe following example, the second front image is displayed at a displaymagnification higher than that of the first front image. Accordingly,the inspector can easily confirm states such as a flare andnon-homogeneous illumination. Naturally, the first front image isdisplayed at a display magnification higher than that of the secondfront image. Accordingly, the inspector can easily confirm a passagestate of a blood vessel, an abnormal portion, and the like. In regard tothe display of the first front image and the second front image, adisplay magnification may be set based on a photographic angle of view.That is, a display magnification may be set corresponding to aphotographic angle of view of an optical system. For example, when theangle of view of the first front image is 30 degrees, and the angle ofview of the second front image is 45 degrees, the second front image maybe displayed at a display size 1.5 times that of the first front image.

For example, the display controller may display the first front image onone (for example, the display unit 95) of a plurality of the displayunits, and the second front image on the other (for example, the displayunit 75) of the plurality of display units.

At least a part of the photographed fundus Ef may be displayed on boththe first front image and the second front image (refer to FIG. 3). Atthis time, when the optical axis of the coherence optical system 200 isdisposed coaxially with the optical axis of the fundus illuminationoptical system 10 and the fundus photography optical system 30, aimaging regions in the vicinity of the optical axes is set as at leastthe same imaging region.

The display controller may be able to superimpose the second front imageon the first front image, or may be able to superimpose the first frontimage on the second front image. For example, in a state where the firstfront image and the second front image are displayed in differentdisplay regions, at least one front image is displayed while beingsuperimposed by the other front image.

The display controller may divisively display the first display region(for example, a display region 300) in which images acquired by thecoherence optical system 200 are integrally displayed, and the seconddisplay region (for example, a display region 400) in images acquired bythe fundus illumination optical system 10 and the fundus photographyoptical system 30 are integrally displayed (refer to FIG. 3).

Accordingly, since a display related to the OCT and a display related tothe fundus front image photography (for example, fundus camera) aredivisively displayed, the inspector can smoothly set various conditions.

For example, the first display region may be provided on a left side inthe display unit, and the second display region may be provided on aright side in the display unit. The first display region and the seconddisplay region may be respectively provided on the right and left sides,or maybe divided vertically.

The first display region may display a tomographic image andphotographic conditions related to the coherence optical system inaddition to the first front image. An example of the photographicconditions related to the coherence optical system 200 may be a scanningposition of the light scanning unit. The scanning position may bechanged based on an operation signal from an operation unit. The displayregion may be provided so as to change an optical path differencebetween the measurement light and the reference light, and the opticalpath difference may be adjusted based on an operation signal input viathe display region.

The second display region may display photographic conditions related toat least either one of the fundus illumination optical system 10 and thefundus photography optical system 20 in addition to the second frontimage. The photographic conditions may include at least any one of thefollowing variables: the position of the focusing lens; the amount ofphotography light emitted from the photography light source 14; aselection between a short exposure photography mode and a normalexposure photography mode; a selection between a small-pupil photographymode and a normal-pupil photography mode; and the like.

The display unit may be a touch panel, or the photographic conditionsmay be changed based on an operation signal input via the touch panel.Naturally, the display unit is not limited to the touch panel, and thephotographic conditions may be changed based on a scanning signaldisplayed on the display unit via an interface such as a mouse or akeyboard.

<Display of Index on Second Front Image>

The device 1 may be provided with an index projection optical systemthat projects an index on the subject's eye. The index projectionoptical system may be at least any one of the following index projectionoptical systems: an index projection optical system (for example, afocus index projection optical system 40) that projects a focus index(for example, a split index) on the fundus of the subject's eye; anindex projection optical system (for example, an infrared light source55) that projects an alignment index on the subject's eye; and an indexprojection optical system that projects a fixation target on thesubject's eye.

Light emitted from the index projection optical system and reflected bythe subject's eye may be imaged by the two-dimensional imaging element(for example, the two-dimensional imaging element 38) of the fundusphotography optical system 30. At this time, the display controller maydisplay indexes (for example, S1, S2, W1, and W2) on the second front,image based on an imaging signal from the two-dimensional imagingelement. A technique of displaying an index may be at least any one ofthe following techniques: a technique of directly displaying an imagedindex; a technique of superimposing an electronic display (for example,a colored display) on an index; a display of an indicator based on aresult of detection of an index position.

<Display of Scanning Line on First Front Image>

The display controller may electronically display a scanning line (forexample, a scanning line SL) on the first front image, the scanning linebeing indicative of a measurement position of a tomographic imagedisplayed on the display unit. Accordingly, it is possible to set ascanning position using the OCT front image on which it is easy toconfirm a state of blood vessels or an abnormal portion.

The scanning line may move based on an operation signal from theoperation unit operated by the inspector. The controller may acquire atomographic image corresponding to the scanning position moved by theinspector. The display controller may not electronically display thescanning line on the second front image.

The display controller may display an index on the second front imagebased on an imaging signal from the two-dimensional imaging element, andelectronically display a scanning line on the first front image, thescanning line being indicative of a measurement position of atomographic image displayed on the display unit. Accordingly, the index(for example, the focus index, the alignment index, or the fixationtarget) displayed on the second front image is not superimposed on thescanning line, and thereby it is possible to easily perform variousadjustments.

<Display of Anterior Chamber Image>

The device 1 may be provided with an anterior chamber observationoptical system 60 for observing an anterior chamber image of thesubject's eye. The display controller may simultaneously display ananterior chamber image acquired by the anterior chamber observationoptical system 60, a tomographic image, the first front image, and thesecond front image.

<Modifications>

As described above, the device 1 may be provided with the indexprojection optical system that projects the index (for example, thefocus index, the alignment index, or the fixation index) on thesubject's eye. At this time, the display controller may display a firstfront observation image of the fundus Ef based on an output signal fromthe light detector or an imaging signal from the two-dimensional imagingelement of the fundus photography optical system 30, the first frontobservation image containing a scanning line indicative of a measurementposition of a tomographic image displayed on the display unit. Inaddition, the display controller may display a second front observationimage of the fundus Ef based on an imaging signal from thetwo-dimensional imaging element of the fundus photography optical system30, the second front observation image containing an index based on theimaging signal from the two-dimensional imaging element. The displaycontroller may simultaneously display the first front observation imageand the second front observation image in different display regions.

Accordingly, the displayed scanning line is not superimposed on thesecond front observation image containing the index, and thereby it ispossible to easily performs an adjustment using the index. At this time,the index may be displayed on the first front observation image. Thereason is that the first front observation image is mainly used to set ascanning position, and it does not comparatively matter whether theindex is present.

The first front observation image and the second front observation imagemay be acquired by the same optical system and imaging element, or maybe acquired by separate optical systems.

When the first front observation image and the second front observationimage may be acquired by the same optical system and imaging element,the controller may control the index projection optical system (forexample, a light source 41 or the light source 55) to turn an index onand off. At this time, the display controller may acquire a frontobservation image at the turning off of the index as the firstobservation image and display the front observation image on the displayunit, and acquire a front observation image at the turning on of theindex as the second observation image and display the front observationimage on the display unit.

<Others>

The application of this control is not limited to the above-mentionedoptical systems in the embodiment, and this control can be applied toother optical systems. For example, the fundus illumination opticalsystem 10 may be an optical system that illuminates the fundus of thesubject's eye by illumination light. The fundus photography opticalsystem 30 may be an optical system that photographs a front image of thefundus illuminated by the illumination light using the photodetector.

As described above, the fundus illumination optical system 10 and thefundus photography optical system 30 may be configured to simultaneouslyilluminate the two-dimensional region of the fundus, and to photograph afront image of the fundus using the photodetector (for example, thetwo-dimensional imaging element). The fundus illumination optical system10 and the fundus photography optical system 30 may be an SLO. The SLOcan photograph a front image of the fundus by scanning a laser beam onthe fundus and receiving reflected light using a photodetector (forexample, a point sensor).

At this time, the display controller may simultaneously display thefirst front image and the second front image in different displayregions. Here, the first front image is based on an output signal fromthe light detector, and the second front image is a front observationimage of the fundus Ef based on a photodetection signal from thephotodetector. Naturally, each of the above-mentioned technologies canalso be applied to this configuration.

Accordingly, it is possible to properly adjust the coherence opticalsystem 200 using the first front image, and the fundus illuminationoptical system 10 or the fundus photography optical system 30 using thesecond front image.

<Second Outline> <Position Alignment Operation Using Front Image>

A photographic operation of the device with the above-mentionedconfiguration will be described. When a photography start switch isoperated, the controller 70 starts to photograph an image. Naturally,the device may be configured such that photography is startedautomatically after the setting of photographic conditions is completed.

In the photographic operation, the controller 70 acquires the firstfront image via a third photography optical system when a first image isacquired via a first photography optical system. In addition, thecontroller 70 acquires the second front image different front the firstfront image via the third photography optical system when a second imageis acquired via a second photography optical system.

For example, the first image is an image of the subject's eyephotographed by a first photography method. The second image is an imageof the subject's eye photographed by a second photography methoddifferent from the first photography method. The front images (the firstfront image and the second front image) are front images of thesubject's eye by a third photography method different from the firstphotography method and the second photography method.

For example, each of the first photography method and the secondphotography method may be configured to use the coherence optical system200, an SLO optical system, the fundus camera optical system 100, theanterior chamber observation optical system 60, a perimeter, and thelike.

For example, the SLO optical system includes a light scanner that scansmeasurement light (for example, the infrared light) emitted from a lightsource in two dimensions, and a photodetector that receivesfundus-reflected light via a confocal opening disposed substantiallyconjugately with the fundus, and the SLO optical system has the sameconfiguration as that of a so-called scanning laser ophthalmoscope(SLO), When a front image of the fundus is acquired, a front image (anSLO image) of the fundus based on a photodetection signal output fromthe photodetector of the SLO.

The fundus camera optical system 100 illuminates the fundus of thesubject's eye by illumination light, and photographs a front image ofthe fundus illuminated by the illumination light. When a method ofphotographing the second image is adopted in the fundus camera opticalsystem 100, the visible light is used as the illumination light, and acolor fundus image is photographed as the second image. At this time,the second photography optical system has a visible light illuminationoptical system that illuminates the fundus of the subject's eye by thevisible light, and a visible light photography optical system thatphotographs a front image of the fundus of the subject's eye illuminatedby the visible light, and the second photography optical systemphotographs a color fundus image of the subject's eye as the secondimage. The color fundus image may be a fluorescent image acquired usingfundus illumination light having a predetermined specified wavelength.

For example, the third photography method may be configured to use thefundus camera optical system 100, the SLO optical system, and the like.When a method of photographing a front image is adopted in the funduscamera optical system 100, the infrared light is used as theillumination light, and an infrared fundus image is photographed as thefront image. At this time, the third photography optical system has aninfrared light illumination optical system that illuminates the fundusof the subject's eye by the infrared light, and an infrared lightphotography optical system that photographs a front image of the fundusof the subject's eye illuminated by the infrared light, and the thirdphotography optical system photographs an infrared fundus image of thesubject's eye as the front images (the first front image and the secondfront image which will be described later).

<Analysis Process>

When the images are acquired, the controller 70 performs an imageanalysis process. The controller 70 detects the amount of positionaldeviation between the first front image and the second front image, andcorrelates the first image with the second image based on the amount ofpositional deviation.

It is possible to easily and accurately correlate the first image withthe second image by correlating the first image with the second imageusing the front images photographed in the same photographic conditions.Since it is possible to rapidly acquire infrared fundus images used asfront images (the first front image and the second front image), whenthe first image is acquired, it is possible to rapidly acquire the frontimages that are positionally aligned when the first image is acquired.In addition, when the second image is acquired, it is possible torapidly acquire the front images that are positionally aligned when thesecond image is acquired. For this reason, there is no nearly positionaldeviation present between the front images and other images (the firstimage and the second image). That is in other words, since it is notnecessary to correlate the positions of the front images with those ofthe other images, the amount of positional deviation between the firstfront image and the second front image can be applied as the amount ofpositional deviation between the first image and the second image. Forthis reason, it is possible to easily and accurately correlate the firstimage with the second image without performing a correlation between theimages multiple times.

Hereinafter, an example of a process in which the controller 70 detectsthe amount of positional deviation between the first front image and thesecond front image and correlates the first image with the second imagebased on the amount of positional deviation will be described. Forexample, a tomographic image is used as the first image. A color fundusimage is used as the second image. An infrared fundus image is used asthe front image. At this time, the controller 70 specifies anacquisition position of a tomographic image of the fundus of thesubject's eye photographed by the first photography optical system on acolor fundus image of the subject's eye photographed by the secondphotography optical system by correlating the tomographic image of thefundus of the subject's eye with the color fundus image of the subject'seye. The controller 70 superimposes a display on the color fundus imageof the subject's eye based on the specified acquisition position, thedisplay being indicative of the acquisition position in which thetomographic image of the fundus of the subject's eye is acquired. Sincethe inspector can accurately understand a correlation between the colorfundus image and the tomographic image which have good resolution andgood contrast, and are suitable to find lesions from the entirety of thefundus, the inspector can perform a useful diagnosis of the subject.

When images are acquired as described in the above-mentioned example,the controller 70 acquires the first front image via the thirdphotography optical system. After the controller 70 acquires the firstfront image, the controller 70 acquires the first image via the firstphotography optical system. After the controller 70 acquires the firstimage, the controller 70 acquires the second image via the thirdphotography optical system. After the controller 70 acquires the secondfront image, the controller 70 acquires the second image via the secondphotography optical system. It is possible to easily photograph thefundus of the subject's eye by acquiring a series of images in theabove-mentioned sequence of image acquisition. That is, when the colorfundus image is first photographed, the pupil of the subject's eye iscontracted, and thereby measurement light for tomographic imagephotography is unlikely to be incident on the subject's eye, and it isdifficult to acquire a tomographic image 83; however, it is possible toeasily acquire a tomographic image 83 and the color fundus image byacquiring a series of images in the above-mentioned sequence of imageacquisition. Also, in a case where front images for correlation areacquired when the tomographic image 83 and the color fundus image areacquired, even though it takes a certain amount of time to acquire thetomographic image, it is possible to easily and accurately correlate thetomographic image with the color fundus image using a first, infraredfundus image acquired when the tomographic image is acquired and asecond infrared fundus image acquired when the color fundus image isacquired.

In addition, in a case where front images for correlation are acquiredwhen the tomographic image and the color fundus image are acquired, andthe tomographic image photography is performed multiple times, it ispossible to easily and accurately correlate a plurality of tomographicimages with the color fundus image without photographing a plurality ofcolor fundus images. For example, the controller 70 acquires infraredfundus images when a plurality of tomographic images are acquired. Thecontroller 70 calculates the amount of positional deviation between eachof the infrared fundus images acquired when the plurality of tomographicimages are acquired, and the second infrared fundus image when the colorfundus image is acquired. The controller 70 correlates the plurality oftomographic images with one color fundus image based on the amount ofpositional deviation between each of the infrared fundus images and thesecond infrared fundus image. Accordingly, it is not necessary toacquire the color fundus image whenever acquiring the tomographic image,and when photographing the color fundus image, it is possible to lessfrequently illuminate the subject's eye by the visible light, and toreduce a burden on the subject. The plurality of tomographic images maybe photographed according to the same scanning pattern, or differentscanning patterns (for example, a line scan, a cross scan, and a mapscan).

The application of the technology of the present invention is notlimited to the device disclosed in this embodiment. For example, anophthalmic photography software (program) to perform the functions ofthe embodiment is supplied to a system or a device via a network orvarious storage media, A computer (for example, a CPU) of the system orthe device can read the program, and execute the program.

For example, the ophthalmic photography program is executed by aprocessor of a control device that controls the operation of anophthalmic photography device configured to photograph the subject'seye. The ophthalmic photography program may be configured to include afirst image acquisition step of acquiring the first image of thesubject's eye by photographing the subject's eye using the firstphotography method; a second image acquisition step of acquiring thesecond image of the subject's eye by photographing the subject's eyeusing the second photography method different from the first photographymethod; a third image acquisition step of acquiring a front image of thesubject's eye by photographing the subject's eye using the thirdphotography method different from the first photography method and thesecond photography method, acquiring the first front image when thefirst image is acquired, and acquiring the second front image differentfrom the first front image when the second front image is acquired; andan image processing step of detecting the amount of positional deviationbetween the first front image and the second front image, andcorrelating the first image with the second image based on the amount ofpositional deviation.

EXAMPLE

As illustrated in FIG. 1( a), a device main body 1 in this examplemainly includes a base 4; a photography unit 3; a face support unit 5;and an operation unit 74. The photography unit 3 may accommodate anoptical system (to be described later). The photography unit 3 may beprovided so as to able to move with respect to the subject's eye E inthree-dimensional directions (X, Y, and Z directions). The face supportunit 5 maybe fixed to the base 4 so as to support a subject's face.

An XYZ drive unit 6 may move the photography unit 3 relative to the eyeE in a lateral direction, a vertical direction (the Y direction), and aforward and backward direction. The photography unit 3 may move withrespect to the right and left eyes in the lateral direction (the Xdirection) and the forward and backward (operation distance) direction(the Z direction) due to the movement of a moving base 2 with respect tothe base 4.

A joystick 74 a is an operation member operated by an inspector so as tomove the photography unit 3 with respect to the eye E. Naturally, theoperation member is not limited to the joystick 74 a, and anotheroperation member (for example, a touch panel or a trackball) may beadopted.

For example, the operation unit transmits an operation signal from theinspector to the controller 70. At this time, the controller 70 may sendthe operation signal to a personal computer 90 (to be described later).In addition, the personal computer 90 sends a control signal to thecontroller 70 in response to the operation signal. When the controller70 receives the control signal, the controller 70 performs variouscontrol operations based on the control signal.

The moving base 2 moves with respect to the subject's eye by theoperation of the joystick 74 a. When a rotating knob 74 b is rotated,the XYZ drive unit 6 is Y driven, and the photography unit 3 moves inthe Y direction. In a case where the moving base 2 is not provided, theXYZ drive unit 6 may be configured to move the photography unit 3 withrespect to the subject's eye when the joystick 74 a is operated.

The photography unit 3 may be provided with the display unit 75 (forexample, the display unit 75 is disposed so as to face the inspector).The display unit 75 may display a fundus observation image, a fundusphotographic image, an anterior chamber observation image, or the like.

The device main body 1 in this example is connected to the personalcomputer (hereinafter, a PC) 90. For example, the display unit 95 andoperation members (for example, a keyboard 96 and a mouse 97) may beconnected to the PC 90.

As illustrated in FIG. 2, the optical system in this example mainlyincludes the illumination optical system 10; the photography opticalsystem 30; and the coherence optical system (hereinafter, also referredto as an OCT optical system) 200. The optical system may further includethe focus index projection optical system 40; the alignment indexprojection optical system 50; and the anterior chamber observationoptical system 60. The illumination optical system 10 and thephotography optical system 30 are used as a fundus camera optical system(an PC optical system) 100 that obtains a color fundus image byphotographing the fundus using visible light (for example, anon-mydriatic state). The photography optical system 30 captures animage of the fundus of the subject's eye. The OCT optical system 200obtains non-invasively a tomographic image of the fundus of thesubject's eye by using optical coherence tomography.

<Fundus Camera Optical System (FC Optical System)>

Hereinafter, an example of an optical disposition of the fundus cameraoptical system 100 will be described.

<Illumination Optical System>

For example, the illumination optical system 10 has an observationillumination optical system and a photography illumination opticalsystem. The photography illumination optical system mainly includes thephotography light source 14; a condensing lens 15; a ring slit 17; arelay lens 18; a mirror 19; a black point plate 20; a relay lens 21; thehole mirror 22, and the objective lens 25. A flashlamp, an LED, or thelike may be used as the photography light source 14. The black pointplate 20 has a black point in a center portion thereof. The photographylight source 14 is used so as to photograph the fundus of the subject'seye using light in a visible bandwidth.

The observation illumination optical system mainly includes theobservation light source 11, an infrared filter 12, a condensing lens13, a dichroic mirror 16, and the optical system from the ring slit 17to the objective lens 25. A halogen lamp, an LED, or the like may beused as the observation light source 11. For example, the observationlight source 11 is used so as to observe the fundus of the subject's eyeusing light in a near-infrared bandwidth. The infrared filter 12 isprovided so as to allow near-infrared light having a wavelength of 750nm or greater to transmit therethrough, and to cut off light having awavelength less than 750 nm. The dichroic mirror 16 is disposed betweenthe condensing lens 13 and the ring slit 17. The dichroic mirror 16 hascharacteristics of reflecting light from the observation light source11, and allowing light from the photography light source 14 to transmittherethrough. The observation light source 11 and the photography light,source 14 may be disposed in series on the same optical axis.

<Photography Optical System>

For example, the objective lens 25, a photographic diaphragm 31, thefocusing lens 32, an imaging lens 33, and the imaging element 35 aremainly disposed in the photography optical system 30. The photographicdiaphragm 31 is positioned in the vicinity of an opening of the holemirror 22. The focusing lens 32 can move in the optical axis direction.The imaging element 35 can be used for sensitive photography in avisible bandwidth. The photographic diaphragm 31 is disposedsubstantially conjugately with the pupil of the subject's eye E withrespect to the objective lens 25. The focusing lens 32 is moved in theoptical axis direction by the driving of a moving mechanism 49 equippedwith a motor.

The dichroic mirror 37 is disposed between the imaging lens 33 and theimaging element 35, and has characteristics of reflecting infrared lightand a part, of visible light and allowing a majority of visible light totransmit therethrough. The observation imaging element 38 havingsensitivity in an infrared bandwidth is disposed in a reflectiondirection of the dichroic mirror 37. A flip-up mirror may be used inplace of the dichroic mirror 34. For example, the flip-up mirror isinserted on the optical path when the fundus is observed, and isretracted when an image of the fundus is photographed.

The insertable and removable dichroic mirror (a wavelength selectiveminor) 24 as an optical path division member is diagonally providedbetween the objective lens 25 and the hole mirror 22. The dichroicmirror 24 reflects the wavelength light of OCT measurement light and thewavelength light (for example, light having a center wavelength λ of 940nm) from the alignment index projection optical system 50 and theanterior chamber illumination light source 58. The dichroic mirror 24has characteristics of allowing light having a wavelength of 800 nm orless to transmit therethrough, the light containing the wavelength (forexample, the center wavelength of 780 nm) of the fundus observationillumination light source. The dichroic mirror 24 is flipped up duringthe photography in conjunction with the driving of an insertion andremoval mechanism 66, and is retracted out of the optical path. Theinsertion and removal mechanism 66 can be configured to include asolenoid, a cam, and the like.

Optical path corrective glass 28 is disposed closer to the imagingelement 35 than the dichroic mirror 24, and can be flipped up by thedriving of the insertion and removal mechanism 66. The optical pathcorrective glass 28 serves to correct the position of the optical axisL1 shifted by the dichroic mirror 24, when being inserted on the opticalpath.

Luminous flax, emitted from the observation light source 11 istransformed into infrared luminous flux by the infrared filter 12, andthe infrared luminous flux is reflected by the condensing lens 13 andthe dichroic mirror 16, and illuminates the ring slit 17. The light thattransmits through the ring slit 17 reaches the hole mirror 22 via therelay lens 18, the mirror 19, the black point plate 20, and the relaylens 21. The light reflected by the hole mirror 22 transmits through thecorrective glass 28 and the dichroic mirror 24, and after the light isconverged in the vicinity of the pupil of the subject's eye E by theobjective lens 25, the light disperses and illuminates the anteriorchamber of the subject's eye.

The reflected light from the fundus is imaged on the imaging element 38via the objective lens 25, the dichroic mirror 24, the corrective glass28, the opening of the hole mirror 22, the photographic diaphragm 31,the focusing lens 32, the imaging lens 33, and the dichroic mirror 37.The imaging element 38 is disposed conjugately with the fundus. Anoutput from the imaging element 38 is input to the controller 70, andthe controller 70 displays a fundus observation image (an OCT frontimage 82) of the subject's eye photographed by the imaging element 38 onthe display unit 75 (refer to FIG. 3).

Luminous flux emitted from the photography light source 14 transmitsthrough the dichroic mirror 16 via the condensing lens 15. Thereafter,the fundus is illuminated by visible light via the same optical path asthat of the illumination light for the observation of the fundus. Thereflected light from the fundus is imaged on the imaging element 35 viathe objective lens 25, the opening of the hole mirror 22, thephotographic diaphragm 31, the focusing lens 32, and the imaging lens33.

<Focus index Projection Optical System>

The focus index projection optical system 40 mainly includes an infraredlight source 41; a slit index plate 42; two declination prisms 43; aprojection lens 47; and a spot mirror 44 diagonally provided on theoptical path of the illumination optical system 10. The two declinationprisms 43 are attached to the slit index plate 42. The spot mirror 44 isdiagonally provided on the optical path of the illumination opticalsystem 10. The spot mirror 44 is fixedly attached to the tip of a lever45. Typically, the spot mirror 44 is provided diagonally with respect tothe optical axis, and is retracted out of the optical path at apredetermined time before the photography by the rotation of the shaftof a rotary solenoid 46.

The spot mirror 44 is disposed conjugately with the fundus of thesubject's eye E. The light source 41, the slit index plate 42, thedeclination prisms 43, the projection lens 47, the spot mirror 44, andthe lever 45 are moved in the optical axis direction in conjunction withthe focusing lens 32 by the driving of the moving mechanism 49. Afterluminous flux from the slit index plate 42 of the focus index projectionoptical system 40 is reflected by the spot mirror 44 via the declinationprisms 43 and the projection lens 47, the luminous flux is projected onthe fundus of the subject's eye E via the relay lens 21, the hole mirror22, the dichroic mirror 24, and the objective lens 25. When the fundusis not in focus, index images S1 and S2 are projected on the funduswhile being separated from each other in response to a deviationdirection and the amount of deviation. In contrast, when the fundus isin focus, the index images S1 and S2 are projected on the fundus whilematching each other (refer to FIG. 3). The index images S1 and S2 arecaptured along with a fundus image by the imaging element 38.

<Alignment Index Projection Optical System>

As illustrated in a dotted line box on the left in FIG. 2, the alignmentindex projection optical system 50 configured to project alignment indexluminous flux has a plurality of infrared light sources disposed at 45degree intervals concentrically about the photography optical axis L1.An ophthalmic photography device in this example mainly includes a firstindex projection optical system (at 0 degrees and 180 degrees) and asecond index projection optical system. The first index projectionoptical system has an infrared light source 51 and a collimating lens52. The second index projection optical system is disposed at a positiondifferent from that of the first index projection optical system, andhas six infrared light sources 53. The infrared light sources 51 aredisposed to be bilaterally symmetrical while a perpendicular planepassing through the photography optical axis L1 is interposed betweenthe infrared light sources 51. In this case, the first index projectionoptical system laterally projects infinite indexes on a cornea of thesubject's eye E. The second index projection optical system isconfigured to vertically or diagonally project finite indexes on thecornea of the subject's eye E, FIG. 2 illustrates the first indexprojection optical system (at 0 degrees and 180 degrees) and only a partof the second index projection optical system (at 45 degrees and 135degrees) for illustrative purposes,

<Anterior Chamber Observation Optical System>

The anterior chamber observation (photography) optical system 60configured to photograph the anterior chamber of the subject's eyemainly includes the dichroic mirror 61, a diaphragm 63, the relay lens64, and the two-dimensional imaging element 65 (a photodetector:hereinafter, may be briefly referred to as the imaging element 65) on areflection side of the dichroic mirror 24. The imaging element 65 hassensitivity in an infrared bandwidth. The imaging element 65 also actsas imaging means for the detection of an alignment index, and capturesan image of the anterior chamber illuminated by infrared light emittedfrom the anterior chamber illumination light source 58 and an image ofthe alignment index. The anterior chamber illuminated by the anteriorchamber illumination light source 58 is received by the imaging element65 via the objective lens 25, the dichroic mirror 24, and the opticalsystem from the dichroic mirror 61 to the relay lens 64. Alignmentluminous flux emitted from the light source of the alignment indexprojection optical system 50 is projected on the cornea of the subject'seye. The cornea-reflected image is received (projected on) by theimaging element 65 via the objective lens 25 to the relay lens 64.

An output from the two-dimensional imaging element 65 is input to thecontroller 70, and as illustrated in FIGS. 3 and 4, the display unit 75displays an anterior chamber image captured by the two-dimensionalimaging element 65. The anterior chamber observation optical system 60is also used as a detection optical system that detects a state ofalignment of the device main body with respect to the subject's eye.

The infrared light sources 55 (in the embodiment, two infrared lightsources 55 are disposed; however, the number of infrared light sources55 is not limited to two) are disposed in the vicinity of a hole of thehole mirror 22, and are used so as to form an optical alignment index (aworking dot W1) on the cornea of the subject's eye. The light source 55may be configured to guide infrared light to an optical fiber, an endsurface of which is disposed in the vicinity of the hole mirror 22. Whenan operation distance between the subject's eye E and the photographyunit (the device main body) 3 is appropriate, the cornea-reflected lightproduced by the light source 55 is imaged on an imaging surface of theimaging element 38. Accordingly, the inspector performs a fineadjustment of alignment using the working dot formed by the light source55 in a state where the fundus image is displayed on a monitor 8.

<OCT Optical System>

The following description is given with reference to FIG. 2. The OCToptical system 200 is configured like a so-called optical coherencetomography (OCT)-based ophthalmic device, and captures a tomographicimage of the eye E. In the OCT optical system 200, a coupler (an opticaldivider) 104 divides light emitted from the measurement light source 102into measurement light (sample light) and reference light. The OCToptical system 200 guides the measurement light to the fundus Ef of theeye E, and guides the reference light to a reference optical system 110.The measurement light reaches the scanning unit 108 via a collimatorlens 123 and a focus lens 124, and a reflected direction of themeasurement light is changed by the driving of two galvanometer mirrors.After the measurement light reflected by the scanning unit 108 isreflected by the dichroic mirror 24, the measurement light concentrateson the fundus of the subject's eye via the objective lens 25. Coherencelight obtained by combining the measurement light reflected by thefundus Ef and the reference light is received by the detector(photodetector) 120.

The detector 120 detects a state of coherence between the measurementlight and the reference Light. When Fourier domain OCT is adopted, thespectral intensity of the coherence light is detected by the detector120, and a predetermined range of a depth profile (A scan signal) isacquired by Fourier-converting spectral intensity data. For example,spectral-domain OCT (SD-OCT) or swept-source OCT (SS-OCT) may beadopted. When the spectral-domain OCT (SD-OCT) is adopted, a widebandwidth light source is used as the light source 102, and aspectrometer is used as the detector 120. When the swept-source OCT isadopted, a variable wavelength light source is used as the light source102, and a single photodiode is used as the detector 120 (the detectionof equilibrium may be performed). In addition, time-domain OCT (TD-OCT)may be adopted.

The scanning unit 108 scans light emitted from the measurement lightsource on the fundus of the subject's eye. For example, the scanningunit 108 scans the measurement light on the fundus in two dimensions (inan X-Y direction (vertical direction)). The scanning unit 108 isdisposed substantially conjugately with the pupil. For example, thescanning unit 108 is two galvanometer mirrors, and a reflected angle ofthe scanning unit 108 is arbitrarily adjusted by a drive unit 151.

Accordingly, a reflected (advance) direction of luminous flux emittedfrom the light source 102 is changed, and is scanned on the fundus in anarbitrary direction. Accordingly, an imaging position on the fundus Efis changed. The scanning unit 108 may be configured to deflect light.For example, an acousto optical modulator (AOM) other than a reflectivemirror (a galvanometer mirror, a polygon mirror, or a resonant scanner)may be used so as to change an advance (deflection) direction of light.

The reference optical system 110 generates the reference light to becombined with the reflected light acquired by the reflection of themeasurement light from the fundus Ef. The reference optical system 110may be Michel son type or may be Mach-Zehnder type.

The reference optical system 110 may change an optical path lengthdifference between the measurement light, and the reference light bymoving an optical member on the reference optical path. For example, areference mirror 131 moves in an optical axis direction. Theconfiguration of changing the optical path length difference may bedisposed on the measurement optical path of the measurement opticalsystem.

More specifically, the reference optical system 110 mainly includes acollimator lens 129, the reference mirror 131, and a reference mirrordrive unit 150. The reference mirror drive unit 150 is disposed on thereference optical path, and is configured such that the reference mirrordrive unit 150 can move in the optical axis direction so as to changethe optical path length of the reference light. The light is reflectedby the reference mirror 131, and thereby the light returns to thecoupler 104 again, and is guided to the detector 120. In anotherexample, the reference optical system 110 may be a transmittance opticalsystem (for example, an optical fiber), and light from the coupler 104does not return, transmits through the transmittance optical system, andis guided to the detector 120.

<Controller>

Subsequently, a control system in this example will be described withreference to FIG. 6. As illustrated in FIG. 6, the following areconnected to the controller 70 in this example: the imaging element 65for anterior chamber observation; the imaging element 38 for infraredfundus observation; the display unit 75; the operation unit 74; a HUB 71compliant with USB 2.0 standards; various light sources (notillustrated); various actuators (not illustrated); and the like. The USB2.0 compliant HUB 71 is connected to the imaging element 35 built intothe device main body 1 and the personal computer (PC) 90.

The PC 90 includes a CPU 91 as a processor; an operation input unit (forexample, a mouse, a keyboard); a memory (a non-volatile memory) 72 asstorage means; and a display unit 95. The CPU 91 may control the devicemain body 1. The memory 72 is a non-transitory storage medium that canmaintain stored content even when the supply of electrical power is shutoff. For example, the memory 72 may be a USB memory insertably andremovably mounted on a hard disc drive, a flash ROM, or the PC 90, anexternal server, or the like. The memory 72 stores a photography controlprogram for controlling the device main body (ophthalmic photographydevice) 1 to photograph a front image and a tomographic image.

The memory 72 stores an ophthalmic analysis program that is used whenthe PC 90 is used as an ophthalmic analysis device. That is, the PC 90may also be used as the ophthalmic analysis device. The memory 72 storesvarious pieces of information regarding photography, for example,information regarding a tomographic image (OCT data) in scanning lines,a three-dimensional tomographic image (three-dimensional OCT data), afundus front image, and a photographic position of a tomographic image.The operation input unit receives various operation instructions fromthe inspector.

The detector (for example, a line CCD) 120 for OCT photography builtinto the device main body 1 is connected to the PC 90 through a USBsignal line via USB ports 79 a and 79 b. In this example, as such, thedevice main body 1 and the PC 90 are connected to each other through twoUSB signal lines 76 and 77.

The controller 70 may detect an alignment index from an anterior chamberobservation image 81 captured by the imaging element 65, and process thealignment index. The controller 70 may detect the amount of deviation ofthe alignment of the device main body 1 with respect to the subject'seye based on an imaging signal from the imaging element 65.

The controller 70 may electronically form and display a reticle (analignment reference) L1 at a predetermined position on a screen of thedisplay unit 75 as illustrated on an anterior chamber image observationscreen in FIG. 4. The controller 70 may control a display of analignment index A1 in such a manner that a relative distance between thealignment index A1 and the reticle LT is changed based on the detectedamount of alignment deviation.

The controller 70 displays the anterior chamber observation imagecaptured by the imaging element 65, and the anterior chamber observationimage captured by the imaging element 38 on the display unit 75 of themain body.

The controller 70 streamingly outputs the anterior chamber observationimage and the fundus observation image to the PC 90 via the HUB 71 andthe USB 2.0 ports 78 a and 78 b. The PC 90 displays the anterior chamberobservation image and the fundus observation image 82 (which arestreamingly output) on the display unit 95 of the PC 90. The anteriorchamber observation image and the fundus observation image (the anteriorchamber observation image 81 and the FC front image 82 in FIG. 3) may besimultaneously displayed as live images (for example, live front images)on the display unit 95.

The imaging element 35 photographs a color fundus image based on atrigger signal from the controller 70. The color fundus image is alsooutput to the controller 70 and the PC 90 via the HUB 71 and the USB 2.0ports 78 a and 78 b, and is displayed on the display unit 75 or thedisplay unit 95 of the PC 90.

In addition, the detector 120 is connected to the PC 90 via the USBports 79 a and 79 b. A photodetection signal from the detector 120 isinput to the PC 90. The PC 90 (more specifically, the processor (forexample. CPU) of the PC 90) generates the tomographic image 83 bycomputationally processing the photodetection signal from the detector120.

For example, when the Fourier domain OCT is adopted, the PC 90 processesa spectroscopic signal containing a coherence signal of each wavelengthoutput from the detector 120. The PC 90 obtains inside information (forexample, depth data of the subject's eye (depth information)) regardingthe subject's eye by processing the spectroscopic signal Morespecifically, the spectroscopic signal (spectral data) is written as afunction of the wavelength λ and is converted into an equal intervalfunction I (k) of a wavenumber k (=2π/λ). The PC 90 obtains a signaldistribution in a depth (in the Z direction) region byFourier-converting the spectroscopic signal in a space of the wavenumberk.

In addition, the PC 90 may obtain information (for example, atomographic image) regarding the subject's eye along with insideinformation obtained at different positions by the scanning ofmeasurement light. The PC 90 stores an obtained result in the memory 72.The PC 90 may display the obtained result on the display unit 95.

The device main body 1 performs photography according to a pre-setscanning pattern based on a release signal from the PC 90. The PC 90processes photographic signals, and outputs an imaging result on thedisplay unit 95 of the PC 90.

At this time, the detector 120 outputs detection signals to the PC 90.The PC 90 generates a tomographic image from the detection signals fromthe detector 120.

The PC 90 transmits the generated tomographic image to the device mainbody 1 via the USB 2.0 ports 78 a and 78 b and the HUB 71. Thecontroller 70 displays the transmitted tomographic image 83 on thedisplay unit 75 (for example, refer to the tomographic image 83). The PC90 may generate an OCT front image from the output signals from thedetector 120, and display the OCT front image 84 on the display unit 75or the display unit 95.

In this example, the inspector can perform set operations such as asetting for OCT photography, alignment, or optimization, or perform apositional alignment, while watching the display unit 75 provided in thedevice main body 1 (details will be described later). Accordingly, asillustrated in FIG. 1( b), the inspector is not required to put effortinto alternately confirming the display unit 75 of the device main body1 and the display unit 95 of the PC 90 which are disposed at differentpositions. In addition, when the inspector opens an eyelid and performsphotography, it may be easier for the inspector to open the eyelid whileconfirming the display unit 75 than opening the eyelid while confirmingthe display unit 95 of the PC 90.

In addition, since the tomographic image 83, the OCT front image 84, theFC front image 82, the anterior chamber observation image 81, and thelike are displayed on both the display unit 75 and the display unit 95of the PC 90, the inspector can preferably select between an operationvia the device main body 1 and an operation via the PC 90, Since variousphotographed images are displayed on both the display unit 75 and thedisplay unit 95 of the PC 90, it is possible to increase the number ofscreens on which images can be observed, and two or more persons caneasily confirm the images.

When one inspector observes images on the display unit 95 of the PC 90,and the other inspector performs photography using the device main body1, that is two inspectors separately perform a measurement, theinspector who performs photography can confirm the photographedtomographic image 83 on the display unit 75, and can redo thephotography when the photography cannot be well performed. For thisreason, it is less frequent for the inspector who observes the displayunit 95 to notify the inspector who performs photography that theredoing of a measurement is required.

In this manner, since the tomographic image 83 is displayed on both thedisplay unit 75 of the device main body 1 and the display unit 95 of thePC 90, the device main body 1 is adaptable to a preferred photographymethod of the inspector.

Similarly, this also applies to the color fundus photography. It may bepossible to not only input a color fundus photography result, to the PC90, but also to transmit image information such as a preview result tothe device main body 1 via the USB 2.0 ports 78 a and 78 b and the HUB71, and to display a color fundus image on the display unit 75 of thedevice main body 1. Accordingly, the inspector is not required to puteffort in alternately confirming the device main body 1 and the PC 90 soas to watch the color fundus image. In a case where the inspectoroperates the device main body 1 while watching the color fundusphotography image, since the inspector is required to confirm only thedisplay unit 75 without glancing the display unit 95 of the PC 90, theinspector has less burden.

<Observation Screen that Displays OCT Front Image and FC Front Image>

An example of a control operation of the device having theabove-mentioned configuration will be described hereinbelow. Forexample, the controller 70 may combine the anterior chamber observationimage captured by the imaging element 65, the fundus observation image(hereinafter, the FC front image) captured by the imaging element 38,the OCT tomographic image (hereinafter, the tomographic image) from thePC 90, and the OCT front image, and display the combined image on anobservation screen on the display unit 75. As illustrated in FIG. 3, theobservation screen may simultaneously display the anterior chamberobservation image 81, the FC front image 82, and the tomographic image83 in a live mode.

FIG. 3 is a view illustrating an example of an observation screenaccording to the embodiment. The controller 70 divisively displays afirst display region 300 and a second display region 400 on the displayunit 75. Here, photographs captured by the coherence optical system 200are integrally displayed in the first display region, and photographscaptured by the fundus illumination optical system 100 are integrallydisplayed in the second display region. In the embodiment, the firstdisplay region 300 and the second display region 400 are formedlaterally side by side; however, naturally, the disposition of the firstdisplay region 300 and the second display region 400 is not limited tothat in the embodiment. For example, the first display region 300 andthe second display region 400 may be disposed vertically side by side.In the example given in the following description, the observationscreen is displayed on the display unit 75; however, the display unit 95may be controlled to display the same observation screen by the PC 90.

The following displays are formed in the first display region 300: anOCT front display region 310 (hereinafter, referred to as a displayregion 310); a scanning position set display (hereinafter, referred toas a set display) 320; a photographic condition display (hereinafter,referred to as a condition display) 330; a tomographic image displayregion (hereinafter, referred to as a display region) 340; and anoptical path difference adjustment display 350.

The OCT front image 84 and the scanning line SL are displayed in thedisplay region 310. The OCT front image 84 (may be simply referred to asa front image 84) is preferably a live image. The controller 70 updatesthe front image 84 displayed in the display region 310 whenever a newOCT front image is acquired. When the OCT front image is displayed in alive mode, the controller 70 may consecutively display the front images84 in real time, or may update the front image at constant timeintervals (for example, every 0.5 seconds).

The scanning line SL is a display for electronically indicating ascanning position (measurement position) on the OCT front image 84. Thecontroller 70 displays the scanning line SL superimposed on the OCTfront image 84. The display pattern of the scanning line SL correspondsto the scanning pattern of the scanning unit 108. For example, when aline scan is set, the scanning line is displayed in a Sine. When a crossscan is set, the scanning line SL is displayed in a cross shape. When amap scan (raster scan) is set, the scanning line is displayed in arectangular shape. A positional relationship between the displayposition of the scanning line SL and the scanning position of thescanning unit 108 is pre-set.

The set display 320 is a display through which the inspector sets thescanning position of the OCT. The controller 70 controls the scanningunit 108 to change a scanning position on the fundus Ef based on anoperation signal input via the set display 320. The controller 70changes the display position of the scanning line SL in conjunction witha change in the scanning position of the scanning unit 108.

The set display 320 of the embodiment has arrows for changing thescanning position the vertical direction and the lateral direction, andarrows for changing the scanning position in a clockwise direction and acounter-clockwise direction. The controller 70 may change the scanningposition by directing operating (for example, a drag scan) the scanningline SL.

The condition display 330 is a display region for illustrating thephotographic conditions of the coherence optical system 200. Forexample, a photography mode, a scanning width, a scanning angle, ascanning density, the frequency of an addition task, and photographicsensitivity are displayed in the condition display 330. The combinationof a photographed portion and a scanning pattern can be selected as thephotography mode, and the selected photography mode is displayed. In thephotography mode illustrated in FIG. 3, a macular area is set as thephotographed portion, and a line scan is set as the scanning pattern. Itis possible to change the photographic condition by operating acondition display displayed in the condition display 330. When acondition display corresponding to the scanning width is operated, thescanning width can be changed.

The OCT tomographic image (hereinafter, the tomographic image) 83 and animage evaluation display 345 are displayed in the display region 340.

The tomographic image 83 is preferably a live image. The controller 70updates the tomographic image 83 displayed in the display region 340whenever a new tomographic image is acquired. When the tomographic imageis displayed in a live mode, the controller 70 may consecutively displaythe tomographic images 83 in real time, or may update the tomographicimage at constant time intervals (for example, every 0.5 seconds).

Here, when the scanning line is changed as described above, thecontroller 70 can display the tomographic image 83 corresponding to thechanged scanning position. When a scanning pattern configured to includea plurality of scanning lines is set, the controller 70 may display atomographic image corresponding to each of the scanning lines.

The image evaluation display 345 is a display for evaluating whether theimage quality of a tomographic image is good, and in the embodiment,evaluation is performed at ten levels using a bar graph. The PC 90analyzes the acquired tomographic image, and evaluates the image basedon an analysis result. The controller 70 displays the analysis resulttransmitted from the PC 90 in the image evaluation display 345. When theanalysis result is rated being low in the image evaluation display 345,the inspector may react to increase the photographic sensitivity, or toadjust the position of the photography unit 3 with respect to thepatent's eye using the anterior chamber observation image 81.

The optical path difference adjustment display 350 is a display regionthrough which an optical path length difference between the measurementlight and the reference light is adjusted. When an automatic adjustmentdisplay (Auto Z) is operated, the controller 70 controls the drive unit150 to automatically adjust the optical path length difference in such amanner that a tomographic image of the fundus is acquired.

When a manual adjustment display (arrows) is operated, the controller 70controls the drive unit 150 to adjust the optical path length differencein response to a direction of the operation and the amount of operation(operation time). Accordingly, the optical path length difference isfinely adjusted by the manual operation performed by the inspector.

Subsequently, the second display region 400 will be described. Thefollowing displays are formed in the second display region 400: an FCfront display region 410; an anterior chamber image display region 420;a photographic condition display (hereinafter, referred to as acondition display) 430; and a pupil diameter determination display 440.

The FC front image 82, focus index images S1 and S2, optical alignmentindex images (optical working dots) W1 and W2 are displayed in thedisplay region 410. The FC front image 82 (may be simply referred to asa front image 82) is preferably a live image. The controller 70 updatesthe FC front image 82 displayed in the display region 410 whenever a newFC front image is acquired. When the FC front image 82 is displayed in alive mode, the controller 70 may consecutively display the FC frontimages 82 in real time, or may update the front image 82 at constanttime intervals (for example, every 0.5 seconds).

When the alignment with respect to the subject's eye is properlyperformed to a certain level, the alignment indexes W1 and W2 appear onthe front image 82 doe to cornea-reflected light formed by the lightsource 55. The observation light is shielded by the lever 45 inserted onthe optical path of the illumination optical system 10, and thereby alight shield region 415 is formed on the imaging element 38, and theoptical focus index images S1 and S2 projected on the fundus are formedat the tip (on the optical axis) of the light shield region 415.

The anterior chamber observation image 81 is formed in the anteriorchamber image display region 420. The anterior chamber observation image81 is preferably a live image. The controller 70 updates the anteriorchamber observation image 81 displayed in the display region 420whenever a new anterior chamber observation image is acquired. When theanterior chamber observation image is displayed in a live mode, thecontroller 70 may consecutively display the anterior chamber observationimages 81 in real time, or may update the anterior chamber observationimage at constant time intervals (for example, every 0.5 seconds). Inthe embodiment, the anterior chamber image display region 420 isdisplayed smaller than the FC front display region 410. Naturally, asizing relationship between the anterior chamber image display region420 and the FC front display region 410 is not limited to that in theembodiment.

The condition display 430 is a display region in which the photographicconditions of the fundus camera optical system 100 are illustrated. Forexample, the following are displayed in the condition display 430: theamount of photography light emitted from the photography light source14; the amount of diopter correction made by the focusing lens 32; aselection of a small-pupil photography mode; a short exposurephotography mode; and the like. It is possible to change thephotographic condition by operating an icon (or a condition display)displayed in the condition display 430. For example, when an iconcorresponding to the amount of photography light is operated, the amountof photography light can be changed.

The pupil diameter determination display 440 displays whether the pupildiameter of the subject's eye satisfies a desired pupil diameter. In theprocessing of the anterior chamber observation image, it is determinedwhether a predetermined pupil diameter is satisfied, and based on aprocess result, it is determined whether the desired pupil diameter issatisfied. The controller 70 changes a display state of the pupildiameter determination display 440 based on a determination result(details will be described later).

The presentation position of the fixation target may be adjusted ineither one of the display regions 310 and the display region 410. Inthis case, a mark indicative of the presentation position of thefixation target is displayed on any one of the front images, and thepresentation position of the fixation target is changed by moving themark on the display unit 75.

When the controller 70 does not acquire the OCT front image 84, thecontroller 70 may display an image in the display region 310, the imagehaving a portion cut out corresponding to the FC front image 82.

<Sequence of Photography>

Hereinafter, an operation of the device will be described. The inspectorgets the subject's face supported by the face support unit 5. Theinspector instructs the subject to watch a fixation target (notillustrated), in an initial stage, the dichroic mirror 24 is inserted onthe optical path of the photography optical system 30, and the displayunit 75 displays the anterior chamber image captured by the imagingelement 65.

The inspector moves the photography unit 3 in the vertical and lateraldirections by adjusting alignment in the vertical and lateraldirections, for example, by operating the joystick 74 a, in such amanner that the anterior chamber image appears on the display unit 75.As illustrated in FIG. 4, when the alignment is adjusted in order forthe anterior chamber image to appear on the display unit 75, eight indeximages (first alignment index images) Ma to Mh appear. At this time, theimaging range of the imaging element 65 preferably includes the pupil ofthe anterior chamber, an iris, and an eyelash when the alignment iscompleted.

<Alignment Detection and Automatic Alignment in X, Y, and Z Directions>

When the alignment index images Ma to Mh are detected by thetwo-dimensional imaging element 65, the controller 70 starts automaticalignment control. The controller 70 detects the amount Δd of deviationof the alignment of the photography unit 3 with respect to the subject'seye based on an imaging signal from the two-dimensional imaging element65. More specifically, an X-Y coordinate of the center of a ring shapeformed by the index images Ma to Mh projected in a ring shape isdetected as a substantially center of the cornea, and the amount Δd ofdeviation between a pie-set alignment reference position O1 (forexample, the intersection of an imaging surface of the imaging element65 and the photography optical axis L1) on the imaging element 65 in theX and Y directions, and the center coordinate of the cornea is obtained(refer to FIG. 7). The center of the pupil may be detected by processingimages, and an alignment deviation may be detected based on the amountof deviation between the coordinate position and the reference positionO1.

The controller 70 controls the driving of the XYZ drive unit 6 toperform automatic alignment in such a manner that the amount Δd ofdeviation is present in an alignment completion allowable range A. Thesuitability of the alignment in the X and Y directions is determinedbased on whether the amount Δd of deviation is continuously present inthe alignment completion allowable range A for a constant amount of time(for example, for 10 frames of the image processing or 0.3 seconds)(whether an alignment condition A is satisfied).

In addition, the controller 70 obtains the amount of alignment deviationin the Z direction by comparing the distance between the infinite indeximages Ma and Me and the distance between the finite index images Mh andMf detected as described above. At this time, the controller 70 obtainsthe amount of alignment deviation with the subject's eye in a directionof the operation distance based on characteristics by which when thephotography unit 3 deviates in the direction of the operation distance,the distance between the infinite index images Ma and Me is not nearlychanged, and the distance between the index images Mh and Mf is changed(specifically, refer to JP-A-6-46999).

The controller 70 also obtains the amount of deviation in the Zdirection with respect to an alignment reference position, and controlsthe driving of the XYZ drive unit 6 to perform automatic alignment insuch a manner that the amount of deviation is present in an alignmentcompletion allowable range. The suitability of the alignment in the Zdirection is determined based on whether the amount of deviation in theZ direction is present in the alignment completion allowable range for aconstant amount of time (whether an alignment condition is satisfied).

When the alignment in the X, Y, and Z directions satisfies the alignmentcompletion condition via the alignment operation, the controller 70determines that the alignment in the X, Y, and Z directions is met, andproceeds to the next step,

Here, when the amount Δd of alignment deviation in the X, Y, and Zdirections is present in an allowable range A1, the controller 70 stopsthe driving of the drive unit 6, and outputs an alignment completionsignal. Even after the alignment is completed, the controller 70frequently detects the amount Δd of deviation, and when the amount Δd ofdeviation exceeds the allowable range A1, the controller 70 restartsautomatic alignment. That is, the controller 70 controls the photographyunit 3 to track the subject's eye in such a manner that the amount Ad ofdeviation is present in the allowable range A1.

<Determination of Diameter of Pupil>

After the alignment is completed, the controller 70 starts a process ofdetermining whether the pupil of the subject's eye is in a suitablestate. At this time, the suitability of a pupil diameter is determinedbased on whether a pupil edge from the anterior chamber image detectedby the imaging element 65 is out of a predetermined pupil determinationarea. The pupil determination area is set to have the size of a diameter(for example, a diameter of 4 mm) around an image center (photographyoptical axis center), through which the fundus illumination luminousflux can pass. In a simple manner, four pupil edges detected laterallyand vertically with respect to the image center are used. When the pupiledge points are out of the pupil determination area, the amount ofillumination light for photography is sufficiently ensured(specifically, refer to JP-A-2005-160549 filed by the applicant). Thesuitability of the pupil diameter is continuously determined until thephotography is performed, a determination result is displayed on thedisplay unit 75.

<Detection of State of Focus and Autofocus>

When the alignment is completed using the imaging element 65, thecontroller 70 performs an autofocus on the fundus of the subject's eye.FIG. 5 illustrates an example of a fundus image captured by the imagingelement 38, and the focus index images S1 and S2 are projected to thecenter of the fundus image by the focus index projection optical system40. Here, when the focus index images S1 and S2 are not in focus, thefocus index images S1 and S2 are projected while being separated fromeach other, and when the focus index images S1 and S2 are in focus, thefocus index images S1 and S2 are projected while matching each other.The controller 70 detects the index images S1 and S2 by processing theimages, and obtain information regarding the separation of the images.The controller 70 controls the driving of the moving mechanism 49 basedon the information regarding the separation of the index images S1 andS2, and moves the lens 32 so as to focus on the fundus.

<Optimization Control>

When an alignment completion signal is output, the controller 70generates a trigger signal for starting optimization control, and startsan optimization control operation. When the controller 70 performs theoptimization control, the inspector can observe a desired fundus portionat high sensitivity and high resolution. In this embodiment, theoptimization control is the controlling of an optical path lengthadjustment, a focus adjustment, and a polarization state adjustment(polarizer adjustment). In the optimization control constant allowableconditions relative to the fundus can be preferably satisfied, and thebest optimized state is not necessarily obtained via the optimizationcontrol.

In an initialization control of the optimization control, the controller70 sets the positions of the reference mirror 131 and the focusing lens124 to initial positions, respectively. After the initialization controlis completed, the controller 70 performs a first optical path lengthadjustment (a first automatic optical path adjustment) by moving thereference mirror 131 from the set initial position by predeterminedsteps in one direction, hi parallel with the first optical path lengthadjustment, the controller 70 acquires focal position information (forexample, the amount of movement of the lens 32) based on a result of afocus on the fundus of the subject's eye performed by the fundus cameraoptical system. When the focal position information is acquired, thecontroller 70 performs an autofocus adjustment (focus adjustment) bymoving the focusing lens 124 to a focal position. The focal position ispreferably a position in which it is possible to acquire an allowablecontrast of a tomographic image as an observation image, and the focalposition is not necessarily an optimized focal position.

After the focus adjustment is completed, the controller 70 performs asecond optical path length adjustment in which an optical path length isre-adjusted (an optical path length is finely adjusted) by moving thereference mirror 131 in the optical axis direction again. After thesecond optical path length adjustment is completed, the controller 70adjusts a polarization state of measurement light by driving a polarizer133 for adjusting a polarization state of reference light (specifically,refer to JP-A-2012-56292).

As such, when the optimization control is completed, the inspector canobserve a desired fundus portion at high sensitivity and highresolution. The controller 70 controls the driving of the scanning unit108 to scan measurement light on the fundus.

A detection signal (spectral data) from the detector 120 is transmittedto the PC 90 via the USB ports 79 a and 79 b (refer to FIG. 6). The PC90receives the detection signal, and generates the tomographic image 83 bycomputationally processing the detection signal.

When the PC 90 generates the tomographic image 83, the PC 90 transmitsthe tomographic image 83 to the controller 70 of the device main body 1via the USB 2.0 ports 78 a and 78 b and the HUB 71. The controller 70receives the tomographic image 83 from the PC 90 via the USB 2.0 ports78 a and 78 b and the HUB 71, and displays the tomographic image 83 onthe display unit 75. As illustrated in FIG. 3, the controller 70displays the anterior chamber observation image 81, the FC front image82, and the tomographic image 83 on the display unit 75.

The inspector confirms the tomographic image 83 which is being updatedreal-time, and adjusts an alignment in the Z direction. For example, thealignment may be adjusted in such a manner that the tomographic image 83is fitted in a display frame.

Naturally, the PC 90 may display the generated tomographic image 83 onthe display unit 95. The PC 90 may display the generated tomographicimage 83 on the display unit 95 in real time. In addition to thetomographic image 83, the PC 90 may display the anterior chamberobservation image 81 and the FC front image 82 on the display unit 95.

In the description, the inspector manually adjusts an image focus byoperating an adjustment knob 74 d or the like; however, the presentinvention is not limited to the method given in this embodiment. Forexample, the inspector may adjust an image by touching the display unit(for example, the display unit 75) having a touch panel function.

When the alignment and the image quality adjustment are completed, thecontroller 70 forms an tomographic image by controlling the driving ofthe scanning unit 108 to scan measurement light on the fundus in apredetermined direction, and acquiring a photodetection signalcorresponding to a predetermined scan region from an output signal fromthe detector 120 during the scanning operation.

FIG. 3 is a view illustrating an example of a display screen displayedon the display unit 75. The controller 70 displays the anterior chamberobservation image 81 acquired by the anterior chamber observationoptical system 60, the FC front image 82, and the tomographic image 83,and a line 85 on the display unit 75. The scanning line 85 is an indexindicative of a measurement position (an acquisition position) for atomographic image on the FC front image 82. The scanning line 85 iselectrically displayed on the FC front image 82 on the display unit 75.

In the configuration of this example, the inspector can set photographicconditions by performing a touch operation or a drag operation on thedisplay unit 75. The inspector can specify an arbitrary position on thedisplay unit 75 via a touch operation.

<Setting of Scanning Line>

When the tomographic image and the OCT front image 84 are displayed onthe display unit 75, the inspector sets a position of a tomographicimage to be photographed on the OCT front image 84 being observed on thedisplay unit 75 in real time. Here, the inspector sets a scanningposition by moving the scanning line 85 with respect to the FC frontimage 82 (for example, a drag operation of the scanning line SL and anoperation of the set display 320). When the line is set in the Xdirection, a tomographic image in an X-Z plane is photographed, and whenthe scanning line 85 is set in the Y direction, a tomographic image inan Y-Z plane is photographed. It may be possible to set the shape of thescanning line 85 to an arbitrary shape (for example, a diagonal line ora circular line).

In this example, the operation of the touch panel display unit 75provided in the device main body 1 has been described; however, thepresent invention is not limited to the operation method given in thisexample. Similar to the display unit 75, it may be possible to operatethe joystick 74 a or various operation buttons provided in the operationunit 74 of the device main body 1. At this time, for example, anoperation signal from the operation unit 74 may be transmitted to the PCvia the controller 70, and the PC may transmit a control signal to thecontroller 70 in response to the operation signal.

When the inspector moves the scanning line SL with respect to the PCfront image 82, the controller 70 frequently sets a scanning position,and acquires the corresponding tomographic image at the scanningposition. The acquired tomographic image is frequently on a displayscreen on the display unit 75. The controller 70 changes a scanningposition of the measurement light based on an operation signal from thedisplay unit 75, and displays the scanning line SL at a display positioncorresponding to the changed scanning position. Since a relationshipbetween the display position (a coordinate position on the display unit)of the scanning line SL and the scanning position of the measurementlight by the scanning unit 108 is determined in advance, the controller70 properly controls the driving of the two galvanometer mirrors of thescanning unit 108 in such a manner that the measurement light is scannedin a scanning range corresponding to the display position of thescanning line SL which is set.

In this configuration, since the OCT front image 84 and the FC frontimage 82 are simultaneously displayed in separate display regions, theinspector can performs the adjustment of a scanning position, theadjustment of the position of the fixation lamp, the adjustment of afocus, the control of a polarized wave, or the like using the OCT frontimage 84, and the inspector can perform the adjustment of alignment, theadjustment of a focus, or the like using the PC front image 82.

At this time, since the OCT front image 84 is a front image formed byscanning light, it is possible to confirm detailed information more thanthe FC front image (for example, it is easy to confirm a passage stateof a blood vessel or an abnormal portion). Accordingly, it is possibleto properly adjust the scanning position.

In contrast, a flare may occur in the FC front image 82 due toreflection by the subject's eye. The inspector can photograph aflare-reduced fundus front image by moving the photography unit 3 withrespect to the subject's eye so as to reduce flaring. Alternatively, theinspector can perform the adjustment of alignment using the opticalalignment indexes W1 and W2. In addition, the inspector can performs theadjustment of a focus using the focus indexes S1 and S2.

When only one of the OCT front image 84 and the FC front image 82 isdisplayed, it is difficult to adjust the coherence optical system 200and the FC optical system 100. In addition, the optical alignmentindexes W1 and W2 and the focus indexes S1 and S2 may be invisible dueto the scanning line. As a result, it is difficult to properly the OCTfront image 84 and the FC front image 82. In contrast, in theembodiment, since both of the OCT front image 84 and the FC front image82 are displayed, it is possible to properly adjust both of the OCTfront image 84 and the FC front image 82.

<Photographic Operation>

As such, after the setting of the photographic conditions is completed,and when the inspector operates the photography start switch 74 c, thecontroller 70 starts to photograph an image. FIG. 8 is a flowchartillustrating the photographic operation. Hereinafter, the photographicoperation will be described with reference to FIG. 8,

First, the controller 70 acquires the FC front image 82 as a still image(a first FC front image) which is illuminated by the observation lightsource 13 and captured by the imaging element 38 (S11). The acquiredfirst FC front image (hereinafter, referred to as the first infraredfundus image) is received by the PC 90 via the HUB 71 and the USB 2.0ports 78 a and 78 b, and thereafter is stored in the memory 72.

Subsequently, the controller 70 acquires a tomographic image (S12). Thecontroller 70 acquires the tomographic image by performing a B scanbased on the set scanning position. The controller 70 drives thescanning unit 108 to scan measurement light in such a manner that atomographic fundus image corresponding to the position of the scanningline SL is obtained based on the display position of the scanning lineSL set on the OCT front image 84.

The PC 90 generates the tomographic image 83 as a still image based on adetection signal from the detector 120. The PC 90 stores the tomographicimage 83 in the memory 72.

When the tomographic image is acquired, the controller 70 re-acquiresthe FC front image 82 as a still image (the second FC front image) whichis illuminated by the observation light source 11 and captured by theimaging element 38 (S13). The acquired second FC front image(hereinafter, referred to as the second infrared fundus image) isreceived by the PC 90 via the HUB 71 and the USB 2.0 ports 78 a and 78b, and thereafter is stored in the memory 72.

Subsequently, the controller 70 proceeds to a step in which a colorfundus image is acquired by the fundus camera optical system 100. Thecontroller 70 retracts the dichroic mirror 24 out of the optical path bydriving the insertion and removal mechanism 66, and controls thephotography light source 14 to emit light.

The fundus of the subject's eye is illuminated by the visible lightemitted from the photography light source 14. The reflected light fromthe fundus passes through the objective lens 25, the opening of the holemirror 22, the photographic diaphragm 31, the focusing lens 32, theimaging lens 33, and the dichroic mirror 37, and is imaged on thetwo-dimensional photodetector 35. The color fundus image photographed bythe two-dimensional photodetector 35 is received by the PC 90 via theHUB 71 and the USB 2.0 ports 78 a and 78 b, and thereafter, the colorfundus image is stored in the memory 72.

In the configuration of the embodiment, after the tomographic image isacquired, the second infrared fundus image and the color fundus imageare automatically acquired; however, the present invention is notlimited to the configuration. For example, after the tomographic imageis acquired, and before the second infrared fundus image and the colorfundus image are acquired, the inspector may performs a fine adjustmentof alignment and a focus. For example, after the tomographic image isacquired, the controller 70 displays an adjustment screen for performinga fine adjustment of alignment and a focus on the display unit 75. Whilethe inspector observes the FC front image 82 displayed on the displayunit 75, the inspector performs a fine adjustment of alignment and afocus so as to be able to photograph the color fundus image in a desiredstate. When the inspector turns on the photography start switch 74 c,the second infrared fundus image and the color fundus image may bephotographed. In this case, when the inspector turns on the photographystart switch 74 c, first, the controller 70 acquires the second infraredfundus image. Alter the controller 70 acquires the second infraredfundus image, the controller 70 acquires the color fundus image.

<Image Analysis Process>

When the acquisition of the tomographic image and the color fundus imageis completed in this manner, the controller 70 matches the tomographicimage and the color fundus image. Accordingly, the controller 70correlates the tomographic image with the color fundus image in terms ofposition.

Hereinafter, the image analysis process for correlating the tomographicimage with the color fundus image in terms of position will hedescribed. In the embodiment, the controller 70 correlates thetomographic image with the color fundus image in terms of position usingthe first infrared fundus image (the first front image) acquired whenthe tomographic image (the first image) is acquired, and the secondinfrared fundus image (the second front image) acquired when the colorfundus image (the second image) is acquired.

For example, the controller 70 detects the amount of positionaldeviation between the first infrared fundus image and the secondinfrared fundus image which are stored in the memory 72, and correlatesthe tomographic image 83 with the color fundus image in terms ofposition.

It is possible to use various image processing techniques (a method ofusing various correlation functions, a method of using Fouriertransform, a method of matching characteristic points) as a technique ofdetecting the amount of positional deviation between the two images.

For example, it may be possible to adopt a technique of deviating theposition of a predetermined reference image (for example, the firstinfrared fundus image) or a target image (the second infrared fundusimage) by one pixel, comparing the reference image with the targetimage, and then detecting the amount of positional deviation betweenboth data when both data best matches with each other (when there is thehighest correlation present between both data). In addition, it may bepossible to adopt a technique of extracting common characteristic pointsfrom the predetermined reference image and the target image, anddetecting the positional deviation of the extracted characteristicpoints.

A phase-only correlation function may be used as a function forobtaining a positional deviation between the two images. In this case,each image is subjected to Fourier transform, and the phase and theamplitude of each frequency component are obtained. The obtainedamplitude component for each frequency component is normalized to thesize of one. Subsequently, after a phase difference for each frequencybetween the two images is calculated, the calculated phase difference issubjected to inverse Fourier transform.

Here, when there is no positional deviation present between the twoimages, only cosine waves are added, and a peak appears at an originposition (0. 0). When there is a positional deviation between theimages, a peak appears at a position corresponding to the positionaldeviation. The amount of positional deviation between the two images isacquired by obtaining the detection position of the peak With thistechnique, it is possible to highly accurately detect the amount ofpositional deviation between the first infrared fundus image and thesecond infrared fundus image in a short amount of time.

In the technique adopted in the embodiment, the controller 70 extractscommon characteristic points from the first infrared fundus image andthe second infrared fundus image, and detects the amount of positionaldeviation of the extracted characteristic points.

When the controller 70 detects the amount of positional deviation, thecontroller 70 correlates the tomographic image 83 with the color fundusimage in terms of position based on the amount of positional deviation.

Here, since the tomographic image 83 and the first infrared fundus imageare acquired at substantially the same time (at completely the sametime), it is possible to pixel-to-pixel correlate both data with eachother. Since the color fundus image and the second infrared fundus imageare acquired at substantially the same time (at completely the sametime), it is possible to pixel-to-pixel correlate both data with eachother. That is, in the embodiment, the first infrared fundus image isacquired, and the tomographic image 83 is rapidly acquired. In addition,the second infrared fundus image is acquired, and the color fundus imageis rapidly acquired. For this reason, there is no nearly positionaldeviation present among the first infrared fundus image, the secondinfrared fundus image, and other images (the tomographic image and thecolor fundus image). For this reason, in other words, it is notnecessary to correlate the first infrared fundus image, the secondinfrared fundus image, and the other images with each other in terms ofposition, and thereby the amount of positional deviation between thefirst infrared fundus image and the second infrared fundus image can beapplied as the amount of positional deviation between the tomographicimage 83 and the color fundus image. For this reason, it is notnecessary to perform a positional deviation between the images multipletimes, and it is possible to easily and accurately correlate thetomographic image 83 with the color fundus image.

For example, the controller 70 corrects the display position of thescanning line SL displayed on the color fundus image based on the amountof positional deviation in such a manner that the tomographic image 83matches with the color fundus image. As described above, since thetomographic image 83 and the first infrared fundus image are acquired atsubstantially the same time, the tomographic image 83 is correlated withthe first infrared fundus image well. That is, the acquisition position(position in which the tomographic image is photographed) of thetomographic image 83 is specified on the first infrared fundus imagebased on the display position of the scanning line SL when theacquisition position of the tomographic image 83 is set on the OCT frontimage 84. Similarly, the color fundus image is also correlated with thesecond infrared fundus image. The controller 70 specifies theacquisition position of the tomographic image 83 on the color fundusimage based on the amount of positional deviation obtained as describedabove. The controller 70 electrically displays the scanning line SL onthe color fundus image based on information regarding the specifiedacquisition position of the tomographic image 83, the scanning line SLbeing indicative of a photographic position in which the tomographicimage is acquired. As such, the controller 70 corrects the displayposition of the scanning line SL to be displayed on the color fundusimage on based on the amount of positional deviation. Accordingly, thecontroller 70 correlates the tomographic image 83 with the color fundusimage in terms of position based on the amount of positional deviation.

When the tomographic image are completely correlated with the colorfundus image in terms of position, the controller 70 transmits theimages and a correlation result to the PC 90 via the HUB 71 and the USB2.0 ports 78 a and 78 b. The PC 90 displays the images and thecorrelation result on the display unit 95. Naturally, the PC 90 maydisplay the images and the correlation result on the display unit 75. Inaddition, the controller 70 may display the images and the correlationresult on the display unit 75.

As such, the tomographic image is not correlated with the color fundusimage, and in contrast, the inspector acquires the front imagesphotographed by the common photography method when the tomographic imageand the color fundus image are acquired, and correlates the tomographicimage with the color fundus image based on the amount of positionaldeviation between the front images photographed by the commonphotography method. Accordingly, it is possible to accurately perform acorrelation between different images (the tomographic image and thecolor fundus image). As described above, the inspector can confirm anacquisition position on the fundus on the color fundus imagecorresponding to the acquired desired fundus tomographic image bycorrelating the tomographic image with the color fundus image.Accordingly, the inspector can accurately understand a correlationbetween the color fundus image and the tomographic image which have goodresolution and good contrast, and are suitable to find lesions from theentirety of the fundus. As a result, the inspector can perform a usefuldiagnosis of the subject.

As described above, the controller 70 acquires a series of images in thesequence of the first front image (for example, the first infraredfundus image), the first image (for example, the tomographic image 83),the second front image (for example, the second infrared front image),and the second image (for example, the color fundus image), and therebyit is possible to easily photograph the fundus of the subject's eye byacquiring a series of images in the above-mentioned sequence of imageacquisition. That is, when the color fundus image is first photographed,the pupil of the subject's eye is contracted, and thereby measurementlight for tomographic image photography is unlikely to be incident onthe subject's eye, and it is difficult to acquire, the tomographicimage; however, it is possible to easily acquire the tomographic imageand the color fundus image by acquiring a series of images in theabove-mentioned sequence of image acquisition.

Also, in a case where the front images for correlation are acquired whenthe tomographic image and the color fundus image are acquired, eventhough it takes a certain amount of time to acquire the tomographicimage, it is possible to easily and accurately correlate the tomographicimage with the color fundus image using the first infrared fundus imageacquired when the tomographic image is acquired, and the second infraredfundus image acquired when the color fundus image is acquired.

In addition, in a case where the front images for correlation areacquired when the tomographic image and the color fundus image areacquired, and the tomographic image photography is performed multipletimes, it is possible to easily and accurately correlate a plurality oftomographic images with the color fundus image without photographing aplurality of color fundus images. For example, the controller 70acquires infrared fundus images when a plurality of tomographic imagesare acquired. The controller 70 calculates the amount of positionaldeviation between each of the first infrared fundus images acquired whenthe plurality of tomographic images are acquired, and the secondinfrared fundus image acquired when the color fundus image is acquired.The controller 70 correlates the plurality of tomographic images withone color fundus image based on the amount of positional deviationbetween each of the infrared fundus images and the second infraredfundus image. Accordingly, it is not necessary to acquire the colorfundus image whenever acquiring the tomographic image, and whenphotographing the color fundus image, it is possible to less frequentlyilluminate the subject's eye by the visible light, and to reduce aburden on the subject. The plurality of tomographic images may bephotographed according to the same scanning pattern, or differentscanning patterns (for example, a line scan, a cross scan, and a mapscan).

In the configuration of the embodiment, the tomographic image 83 isacquired along with the first infrared fundus image, and the colorfundus image is acquired along with the second infrared fundus image,and thereby it is not necessary to re-correlate the first infraredfundus image, the second infrared fundus image, and the other imageswith each other in terms of position; however, the present invention isnot limited to the configuration. The controller 70 may be configured tocorrelate the first infrared fundus image, the second infrared fundusimage, and the other images with each other in terms of position. Forexample, when the controller 70 correlates the tomographic image 83 withthe first infrared fundus image, the controller 70 acquires the OCTfront image 84 as a still image when the tomographic image 83 isacquired. The controller 70 detects the amount of positional deviationbetween the still OCT front image and the first infrared fundus image,and correlates the OCT front image with the first infrared fundus imagein terms of position, based on the amount of positional deviation.Accordingly, the inspector can understand that a predetermined portionon the OCT front image is correlated with a position on the firstinfrared fundus image. That is, it is possible to set the acquisitionposition of the tomographic image on the first infrared fundus image.For example, when the color fundus image is correlated with the secondinfrared fundus image, the controller 70 detects the amount ofpositional deviation between the color fundus image and the secondinfrared fundus image, and correlates the color fundus image with thesecond infrared fundus image in terms of position, based on the amountof positional deviation.

In the embodiment, the tomographic image acquired by the line scan isused as the tomographic image correlated with the color fundus image;however, the present invention is not limited to the tomographic imageacquired by the line scan. For example, a three-dimensional tomographicimage may be used as the tomographic image. In this case, thethree-dimensional tomographic image is correlated with the color fundusimage based on the amount of positional deviation between the infraredfundus images. When the inspector selects a desired position on thecolor fundus image after the photography is completed, the controller 70extracts a tomographic image from the three-dimensional tomographicimage corresponding to the selected position, and displays thetomographic image on the display unit 75.

With the technology of the embodiment, the tomographic image 83 iscorrelated with the color fundus image; however, the present inventionis not limited to the correlation between the tomographic image 83 andthe color fundus image. The technology can be applied to a configurationin which the first image is correlated with the second image. Forexample, the technology can also be applied to the configuration inwhich an analysis map acquired by analyzing the tomographic image iscorrelated with the color fundus image. The technology can also beapplied to the configuration in which the tomographic image iscorrelated with the result of visual field measurement.

In the configuration of the embodiment, two front images (the firstinfrared fundus image and the second infrared fundus image) are acquiredas images used to correlate the tomographic image 83 with the colorfundus image, and a correlation between the two front images isperformed; however, the present invention is not limited to theconfiguration. At least two or more front images may be acquired. In acase where the controller 70 acquires a plurality of front images whenthe first image is acquired, the controller 70 may select front imagesfor correlation in the best photographic state from the plurality offront images. An image in the best photographic state implies the factthat the image has good contrast and a high luminance value.

In the configuration of the embodiment, two front images (the firstinfrared fundus image and the second infrared fundus image) are acquiredas images used to correlate one tomographic image 83 with one colorfundus image; however, the present invention is not limited to theconfiguration. The technology of the present invention can be applied toa case in which a plurality of tomographic images are correlated with aplurality of color fundus images. In this case, the controller 70acquires a plurality of front images along with a plurality of the firstimages. The controller 70 acquires a plurality of front images alongwith a plurality of the second images. Here, when the controller 70selects one tomographic image from the plurality of tomographic images,and correlates the tomographic image with the color fundus images, thecontroller 70 sequentially calculates the amount of positional deviationbetween the selected front tomographic image and the front images of theplurality of color fundus images. The controller 70 may select a colorfundus image from the plurality of color fundus images, which iscorrelated with a front image having the smallest amount of positionaldeviation among the calculated amount of positional deviation, andcorrelate the selected color fundus image with the selected tomographicimage. For example, when the controller 70 selects one tomographic imagefrom the plurality of tomographic images, and correlates the tomographicimage with the color fundus images, the controller 70 compares thephotographic conditions (for example, the amount of light and a fixationposition) of the selected front tomographic image with those of thefront images of the plurality of color fundus images. The controller 70may select a color fundus image from the plurality of color fundusimages, which is correlated with a front image having the most similarphotographic conditions, and correlate the selected color fundus imagewith the selected tomographic image. In the above-mentionedconfiguration, the controller 70 selects one tomographic image from theplurality of tomographic images, and correlates the tomographic imagewith the color fundus image; however, the present invention is notlimited to the configuration. For example, the controller 70 may beconfigured to correlate one selected tomographic image with a pluralityof color fundus images, or may be configured to correlate a plurality oftomographic images with one selected color fundus image. In thisconfiguration, it is possible to perform a correlation between the firstimage and the second image which have a close correlation.

The embodiment may have a configuration in which the blinking of thesubject's eye is detected by comparing the first front image (forexample, the first infrared fundus image) and the second front image(for example, the second infrared fundus image) which are used asreferences tor correlation between different images. For example, thecontroller 70 determines whether the subject's eye is blinked bydetecting the amount of positional deviation between the first infraredfundus image and the second infrared fundus image stored in the memory72, and determining whether the amount of positional deviation isgreater than a predetermined threshold value. For example, when theamount of positional deviation is greater than the threshold value, thecontroller 70 may determine that the subject's eye may be blinked. Thatis, when the subject's eye is blinked, a common area between the frontimages is reduced, and the amount of positional deviation is increased.Accordingly, it is possible to detect the blinking of the subject's eye.The present invention is not limited to a configuration in which theblinking of the subject's eye is detected based on the amount ofpositional deviation between the first infrared fundus image and thesecond infrared fundus image. The blinking of the subject's eye ispreferably detected based on a result of comparison between the firstinfrared fundus image and the second infrared fundus image which areused as references for correlation. For example, the blinking of thesubject's eye may be detected based on whether the similarity betweenthe first front image and the second front image is great. In this case,the controller 70 may determine whether the first front image and thesecond front image are similar to each other by comparing a luminancevalue, contrast, and the like between the first front image and thesecond front image, and determining the level of a correlation.Accordingly, the controller 70 determines that the subject's eye isblinked when the similarity between the images is low. As such, sincethe embodiment has the configuration in which the blinking of thesubject's eye is detected by comparing the first front image acquiredwhen the first image (for example, the tomographic image) is acquiredwith the second front image after the acquisition of the first image iscompleted, and thereby it is possible to detect whether the subject'seye is blinked during the photography of the first image. For thisreason, it is possible to acquire a good first image.

In the embodiment, the amount of positional deviation may be detectedexcept for that of a predetermined region. For example, when thecontroller 70 detects the amount of positional deviation between thefirst front image and the second front image, the controller 70 detectsthe amount of positional deviation except for a predetermined region oneach of the first front image and the second front image. That is, thecontroller 70 excludes potentially problematic portions from a region inwhich the amount of positional deviation is detected. For example, thecontroller 70 sets a predetermined region (for example, a region for aslit index or a region for a working dot) on each of the first infraredfundus image and the second infrared fundus image, and detects theamount of positional deviation in a state where the predeterminedregions are excluded from the computation of the amount of positionaldeviation. The predetermined regions may be excluded based onphotographic conditions (for example, a scanning patter and fixationposition). As such, it is possible to accurately calculate the amount ofpositional deviation by calculating the amount of positional deviationin a state where the region for the split index or the working dot issuperimposed on the fundus in the front images for correlation.Accordingly, it is possible to accurately correlate the first image withthe second image. It is possible to set the excluded predeterminedregion by specifying the problematic portions on front images forcorrelation obtained by photographing a schematic eye, and storing acoordinate position corresponding to the region in the memory 72.Naturally, the excluded predetermined region may be set by detecting theproblematic region from the photographed front images for correlation.

In the configuration of the ophthalmic photograph device of theembodiment, the fundus of the subject's eye is photographed; however,the present invention is not limited to the configuration. Thetechnology can be applied to a case in which the anterior chamber of thesubject's eye is photographed.

Description of Reference Numerals and Signs

1: ophthalmic photography device

70: controller

71: HUB

74: operation unit

75: display unit

76, 77: USB signal line

78 a, 78 b: USB 2.0 port

79 a, 79 b: USB port

90: computer

95: display unit

What is claimed is:
 1. A fundus photography device comprising: an OCToptical system configured to detect interference between a measurementlight from a fundus of a subject's eye and a reference light from areference optical path; a fundus photography optical system configuredto detect a reflected light from the fundus; and a controller configuredto generate a tomographic image of the fundus and a first front image ofthe fundus based on an output signal from the OCT optical system, andgenerate a second front image of the fundus based on an output signalfrom the fundus photography optical system, wherein the controller isconfigured to cause simultaneous display of the first front image andthe second front image in different display regions on a monitor.
 2. Thefundus photography device according to claim 1, wherein the controllercauses display of a first display region integrating displays related tothe OCT optical system, and a second display region integrating displaysrelated to the fundus photography optical system, the first and seconddisplay regions being separated from each other.
 3. The fundusphotography device according to claim 1, further comprising an indexprojection optical system configured to project light of an index ontothe subject's eye; and wherein the controller causes display of an imageof the index on the second front image based on the output signal fromthe fundus photography optical system.
 4. The fundus photography deviceaccording to claim 1, wherein the controller causes the display of ascanning line on the first front image, the scanning line indicating ameasurement position of the tomographic image, and the controllerchanges a display position of the scanning line on the first front imagebased on an operation signal from a user interface and controls anoptical scanner provided in the OCT optical system to change a scanningposition of the measurement light of the fundus, the scanning positionbeing changed corresponding to the display position of the scanningline.
 5. The fundus photography device according to claim 1, wherein thecontroller causes display of an index on the second front image based onthe output signal from the fundus photography optical system, and causesthe display of a scanning line on the first front image, the scanningline indicating a measurement position of the tomographic image, and thecontroller changes a display position of the scanning line on the firstfront image based on an operation signal from a user interface andcontrols an optical scanner provided in the OCT optical system to changea scanning position of the measurement light of the fundus, the scanningposition being changed corresponding to the display position of thescanning line.
 6. The fundus photography device according to claim 1,further comprising an anterior eye photography optical system configuredto detect reflected light from an anterior of the subject's eye, whereinthe controller generates an anterior eye image based on an output signalfrom the anterior eye photography optical system, and causes thesimultaneous display of the anterior eye image with the tomographicimage, the first front image, and the second front image.
 7. The fundusphotography device according to claim 1, wherein the fundus photographyoptical system includes a first two-dimensional imaging sensorconfigured to photograph the fundus, and a second two-dimensionalimaging sensor configured to observe the fundus, and the controllerdisplays the second front image based on an output signal from thesecond two-dimensional imaging sensor.
 8. The fundus photography deviceaccording to claim 1, wherein the fundus photography optical system ispart of a fundus camera optical system.
 9. The fundus photography deviceaccording to claim 1, wherein the fundus photography optical system ispart of a Scanning Laser Ophthalmoscope (SLO) optical system.
 10. Thefundus photography device according to claim 1, wherein the controllersuperimposes a scanning line on the first front image.
 11. The fundusphotography device according to claim 1, wherein the controllergenerates the tomographic image, the first front image, and the secondfront image substantially simultaneously.
 12. The fundus photographydevice according to claim 1, wherein the controller generates thetomographic image, the first front image, and the second front image atsubstantially real time.
 13. The fundus photography device according toclaim 1, wherein the controller causes the simultaneous display of amoving image as the first front image and a moving image as the secondfront image on the monitor.
 14. The fundus photography device accordingto claim 1, wherein the controller causes the simultaneous display ofthe first front image and the second front image on an operation screenof the monitor, the operation screen being configured to operate as auser interface that outputs a control signal by which to operate atleast one of the OCT optical system and the fundus photography opticalsystem.
 15. A fundus photography device comprising: an OCT opticalsystem configured to detect interference between a measurement lightfrom a fundus of a subject's eye and a reference light from a referenceoptical path; a fundus photography optical system configured to detectreflected light from the fundus; an index projection optical systemconfigured to project light of an index onto the subject's eye; and acontroller configured to cause (1) display of a scanning line indicatinga measurement position of a tomographic image on a first front imagegenerated based on an output signal from the OCT optical system or fromthe fundus photography optical system, and (2) display of an image ofthe index on a second front image generated based on the fundusphotography optical system.
 16. A fundus photography device comprising:an interference optical system including: an optical splitter configuredto divide light from an OCT light source into a measurement optical pathand a reference optical path, an optical scanner configured to scanmeasurement light from the measurement optical path onto a fundus of asubject's eye, and a light detector configured to detect combined lightobtained by combining fundus-reflected light produced by the measurementlight reflected by the fundus and reference light from the referenceoptical path; an OCT image processer configured to generate atomographic image of the fundus based on an output signal from the lightdetector, and a first front image that is a front observation image ofthe fundus; a fundus illumination optical system configured tosimultaneously illuminate two-dimensional regions on the fundus of thesubject's eye; a fundus photography optical system configured tophotograph a front image of the fundus with a two-dimensional imagingsensor; and a display controller configured to control a display of amonitor to simultaneously display the first front image and a secondfront image in different display regions, the second front image beinggenerated based on the two-dimensional imaging sensor.